Inclusion Criteria

Studies were considered for inclusion for review, if the following
criteria were met:

English language literature,

Date of publication between January 1, 1995 and June 30, 2007,

Original research reports only (reviews, meta-analyses, structured
reviews, previously published physical activity guidelines, and recommendations
to be retrieved and stored for background information for use by Physical
Activity Guidelines Advisory Committee [PAGAC]),

Peer-reviewed literature only,

Main antecedent or exposure variable is physical activity or
exercise, and

Main health outcome variable or risk factor is clearly described and
fits into one of our health outcome categories.

Exclusion Criteria

The purpose of the Exclusion/Inclusion flow process was to classify
efficiently and accurately references for the abstraction process. The overall
process is a 2-phased system: Studies of physical activity and a diagnosable
health outcome were abstracted during Phase 1, followed by studies of physical
activity and risk factors for the health outcomes, possibly abstracted at a
later date (Phase 2), if requested by the PAGAC. Abstracts that were initially
excluded were coded using a system that will allow for later retrieval, should
it be necessary.

The goal of the Exclusion/Inclusion process was to code references
identified from the "Physical Activity AND Health Outcome" search strategy (see
description of Search Strategy for specific
search terms) into mutually exclusive categories, indicating if they will be
included or excluded for abstraction. Upon initial review, the abstract was
screened by a team leader and assigned one of the following Exclusion/Inclusion
codes:

1 = Yes (Meets screening criteria, will be abstracted);

2 = No (Does not meet screening criteria, will be excluded from further
review); or

Inclusion/Exclusion Coding System

As abstracts were reviewed for exclusion/inclusion, team leaders worked
through the following hierarchical flow system. If an abstract was "stopped" at
any point in the flow process, then the appropriate exclusion code was entered
into Reference Manager in the user-defined "Abstract" cell. The flow system is
described below.

If the reference was coded "1" (YES) or "3" (Phase 2) for abstraction,
the reviewer also coded the "Age group" and "Health outcome" cells in Reference
Manager.

If one team leader was unsure how to triage an abstract, he/she would
consult with another team leader for their input.

The Flow Process

In the first step of the flow process, the reviewer will determine if
the abstract contains an appropriate measure of physical activity. If YES, then
the reviewer will move on to step 2. If NO, the reviewer will enter one of the
following exclusion codes into Reference Manager: 11 = Missing physical
activity; 12 = Single acute bout of exercise; 13 = Specific therapeutic
exercise (Kegel, inspiratory muscle training); 14 = Single measure of physical
fitness (cardiovascular fitness, strength, flexibility); 15 = Not primary
exposure variable or used solely as confounding variable; 16 = Sedentary
behavior (TV viewing, computer games, sleep, other); or 17 = Other.

Definitions of the exclusion codes and examples to illustrate each of
the codes are provided below.

11 = Missing physical activity:

Definition: When the abstract does not contain relevant physical
activity or exercise as listed in the physical activity section of the search
strategy. For example, an abstract might state that the purpose is to examine
"associations between participation in different types of mentally stimulating
leisure activities and status as Alzheimer's disease (AD)." In this case,
leisure activities are mental activities (games and puzzles)  not
activities with large muscle movement (i.e., physical activity) and would
therefore not be eligible.

12 = Single, acute bout of exercise:

Definition: This represents an acute exposure to an exercise or
physical activity session, such as a maximal exercise stress test, a walking
test, or a single session of weight lifting exercises. Health-related responses
often will occur shortly (minutes or hours) after the exposure. For example, in
a study of the effects of resistance exercise on postural control mechanisms in
21 older adults, participants performed three sets of 10-12 repetitions for six
resistance exercises for the lower extremity until fatigue. Immediately after
exercise, postural stability was reduced.

Definition: Where physical activity has the purpose to treat or
rehabilitate a health condition. For example, a study that evaluates a walking
program incorporating real-time biofeedback to reduce asymmetric limb loading
after total hip arthroplasty (THA). In this case, the treadmill walking program
is a therapeutic exercise to help persons with a THA achieve a more symmetric
gait.

Definition: Where the measure of physical activity is based only
on physical fitness measures (single or combined variables). For example, a
study that examines the combined effects of motor speed and knee extension
strength on risk of fall-related bone fractures in elderly individuals over a
10-year period. In this case, motor speed and knee extension strength are
measures of physical fitness.

15 = Not primary exposure variable or used solely as a
confounding variable:

Definition: Where physical activity is used as a secondary
variable only in an analysis. For example, in a study of smoking status and
cardiovascular disease, physical activity may be included as a confounding
variable. If physical activity is not the primary exposure of interest, the
study was excluded.

16 = Sedentary behavior (TV viewing, computer games, sleep,
other):

Definition: Where the measure of physical activity is
characterized by activities that require little energy expenditure. For
example, in a study that examines self-reported sleep and nap habits and risk
of falls and fractures in older women, this exposure (sleeping and napping)
requires little energy expenditure.

17 = Other:

Definition: If the reason for exclusion does not fall into one of
the categories described above, enter this code. For example, a study in which
the purpose was to test the ability of the Transtheoretical Model to predict
exercise stage transition of individuals in a large,
untreated-population-based, random sample of adults (18-65 years of age) over
two consecutive time periods.

Once an eligible abstract is passed to the second step, the reviewer
will next determine if the health outcome is appropriate for abstraction. We
abstracted in two phases, where "Phase 1" consisted of the diagnosable or
so-called "hard" health outcomes, and "Phase 2" consisted of the "risk factors"
for the Phase 1 outcomes. If the health outcome was deemed appropriate for
Phase 1 abstractions, the reviewer moved to step 3. If not, the reviewer
entered one of the following exclusion codes into Reference Manager: 21 =
Missing health outcome; 22 = Inappropriate health outcome (see Phase 1 health outcome list); 23 = Phase 2
health outcome (see Phase 2 health outcome
list); 24 = Study of physical activity correlates; or 25 = Other.

21 = Missing health outcome

Definition: If the abstract does not include a
Phase 1 or Phase 2 health outcome, enter this code.

Definition: If the outcome described in the
abstract is a Phase 2 outcome, enter this code.

24 = Study of physical activity correlates

Definition: If the primary purpose of the study
is to examine characteristics associated with physical activity (i.e.,
correlates), enter this code.

25 = Other

Definition: If the reason for exclusion does not
fall into one of the categories described above, enter this code.

In the third step, the reviewer will determine if the article is of an
appropriate format to abstract. If not, the reviewer will enter one of the
following exclusion codes into Reference Manager: 31 = Review, meta-analysis,
no abstract; 32 = Case report; or 33 = Other.

31 = Review, meta-analysis, no abstract

Definition: If the abstract is a review article,
meta-analysis, or does not have an abstract, enter this code.

32 = Case report

Definition: If the abstract is a case report
(single case) or case series (multiple cases), enter this code.

33 = Other

Definition: If the reason for exclusion does not
fall into one of the categories described above, enter this code. For example:
a study that examines the contribution of infant and caregiving conditions to
the quantity of focused exploration of toys for 8-month-old infants.

34 = Injury as health outcome with no variation in the physical
activity exposure

Definition: If there is no variation in physical
activity exposure, enter this code. For example, a study of injuries among rock
climbers is coded as "exclude" code "34," because there is no variation in the
physical activity exposure of rock climbing.

35 = Physical activity as health outcome in a cross-sectional
study

Definition: In cross-sectional studies of
physical activity and a health outcome (e.g., BMI), if physical activity is the
outcome (dependent) measure in the analysis, enter this code. For example, mean
minutes of leisure time physical activity are reported for two categories of
BMI (overweight and obese).

41 = Study design or study characteristics are not acceptable for
Phase 2 abstraction as designated by the Federal Advisory Committee

*There are exceptions to this model. Studies with an appropriate health
outcome and with physical activity classified as shown below will be included
and coded:

If the study:

(1) Is an experimental study where physical activity + diet (non-drug)
is a treatment arm.

(2) Is an experimental study where the treatment arms are able to test
the singular effect of physical activity. For example, in a study that included
two treatment arms: (1) Physical Activity + Treatment X versus (2) Treatment X.

(3) Studies where the physical activity exposure is based on group
membership (not individually assessed  e.g., occupational category;
athletic/sport participation, etc.) will be included.